generate one aabbWall

Asked by Christian Jakob on 2011-12-01

Hi,

For a model with periodic space (in 2 directions) I need only one wall/facet.
I have to create a layer of facets, because they are bodies and no body should be "larger than half of the cell size".
I used the following command to get my "facet-layer"

for ii in range(1,4):
 for jj in range(1,4):
  id_facets=O.bodies.append(geom.facetBox((((2*ii-1)/6.0)*x_cu,((2*jj-1)/6.0)*y_cu,z_cl),((x_cu-x_cl)/6.0,(y_cu-y_cl)/6.0,0),fixed=True,material=FacetMat))

I heard that facets have knows bugs and I want to avoid using facets, so I tried to use aabbWalls. But with this command automatically 6 walls are created, so I have to delete 5 of them:

wall=utils.aabbWalls(material=FacetMat)
wallId=O.bodies.append(wall)
for ii in range(0,len(wallId)):
 if ii != 4:
  O.bodies.erase(wallId[ii]) #erase all walls except the boddom wall (wallId[4])

Ok, now I have the same problem with the body size:

2280 FATAL yade.ThreadRunner /home/me/YADE/yade/core/ThreadRunner.cpp:31 run: Exception occured:
/home/me/YADE/yade/pkg/common/InsertionSortCollider.cpp: Body larger than half of the cell size encountered

Now my questions:
1) Is it possible to create only 1 wall, instead of 6 and deleting 5 of them?
2) Is it possible to create one wall, that is bigger than half of the cell size, without getting the error message?
I know, that in PFC this is possible, because walls and particles are not in the same class/category.

Question information

Language:
English Edit question
Status:
Solved
For:
Yade Edit question
Assignee:
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Solved by:
Bruno Chareyre
Solved:
2011-12-02
Last query:
2011-12-02
Last reply:
2011-12-01

1) see https://www.yade-dem.org/doc/yade.utils.html#yade.utils.box

2) Currently no. We are facing the same problem with Donia Marzougui, and I wonder if we will not relax this half-size constraint somehow. In this situation, it forbids a simulation that could otherwise run normally. I need more thinking before trying something.
Alternatives are collection of facets, with the problem you mention, or blocked DOFs for spheres of the top and bottom layers.

>For a model with periodic space (in 2 directions) I need only one wall/facet.

You need in fact two (top/bottom) or I miss something?

Christian Jakob (jakob-ifgt) said : #3

Thank for your comments, no I need only one.
The upper layer of particles will be clumped together. Then the
mass/density of this layer will be increased for simulating a defined
depth/stress.

Zitat von Chareyre <email address hidden>:

> Your question #180603 on Yade changed:
> https://answers.launchpad.net/yade/+question/180603
>
> Chareyre posted a new comment:
>> For a model with periodic space (in 2 directions) I need only one
> wall/facet.
>
> You need in fact two (top/bottom) or I miss something?
>
> --
> You received this question notification because you asked the question.
>

Anton Gladky (gladky-anton) said : #4

Christian, you can create one large facet, which covers all your packing.
I did it for some simulations.

The known facet problem will unlikely affect you.

Anton

On Thu, Dec 1, 2011 at 5:41 PM, Christian Jakob
<email address hidden> wrote:
> Question #180603 on Yade changed:
> https://answers.launchpad.net/yade/+question/180603
>
>    Status: Answered => Open
>
> Christian Jakob is still having a problem:
> Thank for your comments, no I need only one.
> The upper layer of particles will be clumped together. Then the
> mass/density of this layer will be increased for simulating a defined
> depth/stress.
>
> Zitat von Chareyre <email address hidden>:
>
>> Your question #180603 on Yade changed:
>> https://answers.launchpad.net/yade/+question/180603
>>
>> Chareyre posted a new comment:
>>> For a model with periodic space (in 2 directions) I need only one
>> wall/facet.
>>
>> You need in fact two (top/bottom) or I miss something?
>>
>> --
>> You received this question notification because you asked the question.
>>
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
>
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One big facet will break periodicity Anton. Or there is a trick?

Anton Gladky (gladky-anton) said : #6

Sorry, I did not pay attention, that you are talking about periodicity.

Anton

Christian Jakob (jakob-ifgt) said : #7

Thanks Chareyre, that solved my question.

Christian, 3D-periodicity can also be used to apply vertical pressure. Maybe it would apply in your case?

Christian Jakob (jakob-ifgt) said : #9

Sure, but I dont know the pressure in a certain depth. I want to use depth itself as input parameter.